earth science

Sunda Trench

Sunda Trench is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sunda Trench rather than just read about it. In short: The Sunda Trench, earlier known as and sometimes still indicated as the Java Trench, is an oceanic trench located in the Indian Ocean near Sumatra, formed where the Australian-Capricorn plates subduct under a part of the Eurasian plate. It is 3,200 kilometres (2,000 mi) long with a maximum depth of 7,290 metres (23,920 feet).

Key takeaways

Sunda Trench belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sunda Trench to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sunda Trench from memory before moving on to harder problems.

Reference excerpt

The Sunda Trench, earlier known as and sometimes still indicated as the Java Trench, is an oceanic trench located in the Indian Ocean near Sumatra, formed where the Australian-Capricorn plates subduct under a part of the Eurasian plate. It is 3,200 kilometres (2,000 mi) long with a maximum depth of 7,290 metres (23,920 feet). Its maximum depth is the deepest point in the Indian Ocean. The trench stretches from the Lesser Sunda Islands past Java, around the southern coast of Sumatra to the Andaman Islands, and forms the boundary between the Indo-Australian plate and Eurasian plate (more specifically, Sunda plate). The trench is considered to be part of the Alpide belt as well as one of oceanic trenches around the northern edges of the Australian plate.

In 2005, scientists found evidence that the 2004 earthquake activity in the area of the Java Trench could lead to further catastrophic shifting within a relatively short period, perhaps less than a decade. This threat has resulted in international agreements to establish a tsunami warning system in place along the Indian Ocean coast.

Characteristics

For about half its length, off of Sumatra, it is divided into two parallel troughs by an underwater ridge, and much of the trench is at least partially filled with sediments. Mappings after the 2004 Indian Ocean earthquake of the plate boundary showed a resemblance to suspension bridge cables, with peaks and sags, indicative of asperity and locked faults, instead of the traditional wedge shape expected.

Exploration Some of the earliest explorations of the trench occurred in the late 1950s when Robert L. Fisher, a research geologist at the Scripps Institution of Oceanography, investigated the trench as part of a worldwide scientific field exploration of the world's ocean floor and sub-oceanic crustal structure. Bomb-sounding, echo-train analysis, and manometer were some of the techniques used to determine the depth of the trench. The research contributed to an understanding of the subduction characteristic of the Pacific margins. Various agencies have explored the trench in the aftermath of the 2004 earthquake, and these explorations have revealed extensive changes in the ocean floor.

Crewed descent

On 5 April 2019 Victor Vescovo made the first crewed descent to the deepest point of the trench in the Deep-Submergence Vehicle Limiting Factor (a Triton 36000/2 model submersible) and measured a depth of 7,192 m (23,596 ft) ±13 m (43 ft) by direct CTD pressure measurements at 11°7'44" S, 114°56'30" E, about 500 km (310 miles) south of Bali. The operating area was surveyed by the support ship, the Deep Submersible Support Vessel DSSV Pressure Drop, with a Kongsberg SIMRAD EM124 multibeam echosounder system. The gathered data was donated to the GEBCO Seabed 2030 initiative. The dive was part of the Five Deeps Expedition. The objective of this expedition is to thoroughly map and visit the deepest points of all five of the world's oceans by the end of September 2019. To resolve the debate regarding the deepest point of the Indian Ocean, the Diamantina fracture zone was surveyed by the Five Deeps Expedition in March 2019, recording a maximum water depth of 7,019 m (23,028 ft) ±17 m (56 ft) at 33°37'52" S, 101°21'14" E for the Dordrecht Deep. This confirmed that the Sunda Trench was indeed deeper than the deepest location in the Diamantina Fracture Zone.

Associated seismicity

The subduction of the Indo-Australian plate beneath a bloc of the Eurasian plate is associated with numerous earthquakes. Several of these earthquakes are notable for their size, associated tsunamis, and/or the number of fatalities they caused.

Sumatra segment 1797 Sumatra earthquake: magnitude 8.6–8.8 1833 Sumatra earthquake: magnitude 8.8–9.2 1861 Sumatra earthquake: magnitude ~8.5 1935 Sumatra earthquake: magnitude 7.7 2000 Enggano earthquake: magnitude 7.9 2002 Sumatra earthquake: A magnitude 7.3 earthquake that occurred at the boundary between the rupture areas of the 2004 and 2005 earthquakes listed below. 2004 Indian Ocean earthquake and tsunami: Mw 9.2–9.3 2005 Nias–Simeulue earthquake: magnitude 8.6 2007 Bengkulu earthquakes: Series of earthquakes, the three largest were magnitude 8.5, 7.9, and 7.0. 2008 Simeulue earthquake: magnitude 7.4 near the 2002 event. 2009 Sumatra earthquakes: magnitude 7.6 2010 Mentawai earthquake and tsunami: magnitude 7.8

Java segment 1917 Bali earthquake: magnitude 6.6 1994 Java earthquake: magnitude 7.8 2006 Pangandaran earthquake and tsunami: magnitude 7.7 2009 West Java earthquake: magnitude 7.0 2019 Sunda Strait earthquake: magnitude 6.9

See also Banda Arc List of islands of Indonesia Plate tectonics Sunda Arc Sunda Islands Greater Sunda Islands Lesser Sunda Islands Sundaland Oceanic trench

References

Further reading Špičák, A., V. Hanuš, and J. Vaněk (2007), Earthquake occurrence along the Java trench in front of the onset of the Wadati–Benioff zone: Beginning of a new subduction cycle?, Tectonics, 26, TC1005

Illustrations

Worked examples

Example 1 — a first encounter with Sunda Trench

Start with the simplest possible case. Write down what Sunda Trench claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sunda Trench before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sunda Trench ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sunda Trench

In research: Sunda Trench appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sunda Trench in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sunda Trench is common in secondary-school and first-year university syllabi. It links to neighbouring topics Extreme points of Asia, Geology of Indonesia, Lowest points of the World Ocean, so understanding it makes those chapters shorter.
In everyday life: Look for Sunda Trench outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sunda Trench in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sunda Trench means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sunda Trench out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sunda Trench in simple terms?

Why does Sunda Trench matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sunda Trench?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sunda Trench.